Provide builder for ResponseEntity

This commit introduces a ResponseEntityBuilder, which allows for
building of a ResponseEntity through a fluent API.

Issue: SPR-11752

spring-web/src/test/java/org/springframework/http/ResponseEntityBuilderTests.java

@@ -0,0 +1,133 @@
+/*
+ * Copyright 2002-2014 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.http;
+
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.Collections;
+import java.util.List;
+
+import static org.junit.Assert.*;
+import org.junit.Test;
+import static org.springframework.http.ResponseEntityBuilder.*;
+
+public class ResponseEntityBuilderTests {
+
+	@Test
+	public void normal() {
+		String headerName = "My-Custom-Header";
+		String headerValue1 = "HeaderValue1";
+		String headerValue2 = "HeaderValue2";
+		Object entity = new Object();
+
+		ResponseEntity<Object> responseEntity =
+				status(HttpStatus.OK).header(headerName, headerValue1, headerValue2).body(entity);
+
+		assertNotNull(responseEntity);
+		assertEquals(HttpStatus.OK, responseEntity.getStatusCode());
+		assertTrue(responseEntity.getHeaders().containsKey(headerName));
+		List<String> list = responseEntity.getHeaders().get(headerName);
+		assertEquals(2, list.size());
+		assertEquals(headerValue1, list.get(0));
+		assertEquals(headerValue2, list.get(1));
+		assertEquals(entity, responseEntity.getBody());
+	}
+
+	@Test
+	public void okNoBody() {
+		ResponseEntity<?> responseEntity = ok().build();
+
+		assertNotNull(responseEntity);
+		assertEquals(HttpStatus.OK, responseEntity.getStatusCode());
+		assertNull(responseEntity.getBody());
+	}
+
+	@Test
+	public void okEntity() {
+		Object entity = new Object();
+		ResponseEntity<Object> responseEntity = ok(entity).build();
+
+		assertNotNull(responseEntity);
+		assertEquals(HttpStatus.OK, responseEntity.getStatusCode());
+		assertEquals(entity, responseEntity.getBody());
+	}
+
+	@Test
+	public void createdLocation() throws URISyntaxException {
+		URI location = new URI("location");
+		ResponseEntity<?> responseEntity = created(location).build();
+
+		assertNotNull(responseEntity);
+		assertEquals(HttpStatus.CREATED, responseEntity.getStatusCode());
+		assertTrue(responseEntity.getHeaders().containsKey("Location"));
+		assertEquals(location.toString(),
+				responseEntity.getHeaders().getFirst("Location"));
+		assertNull(responseEntity.getBody());
+	}
+
+	@Test
+	public void acceptedNoBody() throws URISyntaxException {
+		ResponseEntity<?> responseEntity = accepted().build();
+
+		assertNotNull(responseEntity);
+		assertEquals(HttpStatus.ACCEPTED, responseEntity.getStatusCode());
+		assertNull(responseEntity.getBody());
+	}
+
+	@Test
+	public void noContent() throws URISyntaxException {
+		ResponseEntity<?> responseEntity = ResponseEntityBuilder.noContent().build();
+
+		assertNotNull(responseEntity);
+		assertEquals(HttpStatus.NO_CONTENT, responseEntity.getStatusCode());
+		assertNull(responseEntity.getBody());
+	}
+
+	@Test
+	public void headers() throws URISyntaxException {
+		String eTag = "\"foo\"";
+		URI location = new URI("location");
+		long contentLength = 67890;
+		MediaType contentType = MediaType.TEXT_PLAIN;
+
+		ResponseEntity<?> responseEntity = ResponseEntityBuilder.ok().
+				allow(Collections.singleton(HttpMethod.GET)).
+				eTag(eTag).
+				lastModified(12345L).
+				location(location).
+				contentLength(contentLength).
+				contentType(contentType).
+				build();
+
+		assertNotNull(responseEntity);
+		assertEquals(HttpStatus.OK, responseEntity.getStatusCode());
+		HttpHeaders responseHeaders = responseEntity.getHeaders();
+
+		assertEquals("GET", responseHeaders.getFirst("Allow"));
+		assertEquals(eTag, responseHeaders.getFirst("ETag"));
+		assertEquals("Thu, 01 Jan 1970 00:00:12 GMT",
+				responseHeaders.getFirst("Last-Modified"));
+		assertEquals(location.toASCIIString(),
+				responseHeaders.getFirst("Location"));
+		assertEquals(String.valueOf(contentLength), responseHeaders.getFirst("Content-Length"));
+		assertEquals(contentType.toString(), responseHeaders.getFirst("Content-Type"));
+
+		assertNull(responseEntity.getBody());
+	}
+
+
+}